There are legitimate reasons for governments to do sigint, but I think the burden of proof should be on them to show that increased sigint capability would have done anything to prevent this attack.<p>So far I've seen remarkably bupkis in terms of concrete reasoned arguments in this area. I'd like someone from e.g. the NSA or GCHQ to give a presentation in which they show that it is feasible to spot terrorist activity in an ocean of otherwise normal data and differentiate it from e.g. morons talking trash that they'll never act upon, gamers talking about in-game terrorism, lesser criminal activity, non-criminal dissent, and other background noise. My strong intuition is that this is statistically and mathematically impossible and you'd drown in false positives, but I'd be open to a convincing argument if these agencies wanted to dignify the public with such an explanation.<p>Unless such evidence can be furnished, then all this mass surveillance data mining to "stop terror" amounts to a kind of modern superstition. Back in ancient times priests collected a lot of money from kings and from the public in exchange for entrail-gazing and astrological rites to guarantee success in battle or ward off a poor growing season. None of that crap worked, and I doubt that big-data entrail gazing works either.